Iran's top legislative body has ruled out annulling a disputed presidential poll that has prompted the biggest street protests since the 1979 Islamic revolution, but said it was prepared for a partial recount.

In what appeared to be a first concession by authorities to the protest movement, the 12-man Guardian Council said it was ready to re-tally votes in the poll, in which hardline President Mahmoud Ahmadinejad was declared the runaway winner.

But the powerful council rejected reformist calls to annul Friday's election, which set off swift-moving political turmoil in which at least seven people were killed in clashes with security forces in the capital Tehran.

State television said the "main agents" in post-election unrest had been arrested with explosives and guns. It gave no further details.

Supporters of Mir Hossein Mousavi, outraged at what they viewed as a stolen election, had planned another big rally on Tuesday but were urged not to attend in order to "protect their lives" in the wake of Monday's deadly violence.

But state television showed live pictures of thousands of Ahmadinejad supporters, some waving Iranian flags, gathering at the Vali-ye Asr Square.

Illustrating Iran's sensitivity to world opinion, authorities on Tuesday banned foreign journalists from leaving their offices to cover street protests.

Further protests, especially if they are maintained on the same scale, would be a direct challenge to the authorities who have kept a tight grip on dissent since the US-backed shah was overthrown in 1979 after months of demonstrations.

Recount

A spokesman for the Guardian Council, which groups clerics and Islamic law experts as a constitutional watchdog, said that it was "ready to recount the disputed ballot boxes claimed by some candidates, in the presence of their representatives".

"It is possible that there may be some changes in the tally after the recount," spokesman Abbasali Kadkhodai said.

"Based on the law, the demand of those candidates for the cancellation of the vote, this cannot be considered."